1. Field of the Invention
The present invention relates to a flexible tubular portion of an endoscope, and an endoscope having the flexible tubular portion.
2. Description of the Related Art
In general, an endoscope has a flexible tubular portion. A flexible tubular portion is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 11-285469. The flexible tubular portion includes, for example, a metallic spiral tube portion, a mesh tube portion which is provided outside the spiral tube portion and which covers the spiral tube portion, and an outer tube which is provided outside the mesh tube portion and which covers the mesh tube portion. The mesh tube portion is stacked on the spiral tube portion, and the outer tube is stacked on the mesh tube portion. Thus, the flexible tubular portion has a three-layer structure.
The flexible tubular portion has a flexibility, and is therefore flexed, for example, when a load is applied thereto. In this case, the load is proportional to the flexing amount (deformation amount), and the flexing amount is greater when the load is higher. This load is, for example, an external pressure received from the intestines when the flexible tubular portion is inserted into the large intestine and abuts on a flection such as the sigmoid colon in the large intestine.